Very thin air that surrounds watering hole (6)
I believe the answer is:
skinny
'very thin' is the definition.
(I've seen this before)
'air that surrounds watering hole' is the wordplay.
'air' becomes 'sky'.
'that surrounds' indicates putting letters inside.
'watering hole' becomes 'inn' (both can mean a drinking establishment).
'sky' going around 'inn' is 'SKINNY'.
(Other definitions for skinny that I've seen before include "Of person, very thin" , "stout? Certainly not!" , "Spare: coffee with skimmed milk" , "far from stout!" , "Not very well-built" .)